Jesse Jackson Jr. in Mayo Clinic for depression

FILE - In this Oct. 16, 2011 file photo, Rep. Jesse Jackson, Jr., D-Ill., is seen during the dedication of the Martin Luther King Jr. Memorial in Washington. The Mayo Clinic says Illinois Congressman Jesse Jackson Jr. is being treated for depression at its hospital in Rochester, Minn. (AP Photo/Charles Dharapak, File)

ROCHESTER, Minn. (AP) — Illinois Congressman Jesse Jackson Jr., whose whereabouts haven't been disclosed since he quietly took a medical leave from Congress several weeks ago, is being treated for depression at the Mayo Clinic in Minnesota, according to a statement released by the hospital.

Jackson is undergoing an extensive inpatient evaluation for depression and for gastrointestinal issues, the hospital said, providing the first details about his medical condition. But the statement released late Friday didn't disclose where the longtime Chicago congressman, the son of civil rights leader Jesse Jackson, had previously been staying.

"Further information will be released as Congressman Jackson's evaluation proceeds," the statement said, adding that he and his family were "grateful for the outpouring of support and prayers that have been received throughout his care."

Phone messages left by The Associated Press for his spokesman weren't returned Friday. In 2004, Jackson underwent a procedure to help him lose weight that involves removing part of the stomach and rearranging the intestine.

The Democrat went on leave June 10, though his office didn't disclose it until weeks later and has been mum on details ever since. Initially, his office said Jackson was being treated for exhaustion. But his staff later said Jackson's condition was more serious and required inpatient medical treatment. They also said Jackson has been grappling with emotional issues.

Under mounting pressure from his colleagues and constituents, his office released a statement last month from his unnamed doctor saying Jackson was receiving intensive medical treatment at a residential treatment facility for "a mood disorder."

The timing of his medical leave has raised questions, in part because Jackson is facing an ethics investigation in the U.S. House connected to imprisoned former Illinois Gov. Rod Blagojevich.

The House Ethics Committee is investigating allegations that Jackson was involved in discussions about raising money for Blagojevich's campaign in exchange for the then-governor appointing him to President Barack Obama's vacated U.S. Senate seat. Blagojevich is serving a 14-year prison sentence for corruption.

Jackson was not charged and has repeatedly denied wrongdoing.

Jackson faces a Republican and independent candidate in November, though he's widely expected to win re-election. He first won office in a 1995 special election and has easily won each race since. His district includes parts of Chicago and some suburbs.